I can't use the dashboor

I installed Mailbulter, opened gmail, logged in and can view all the features but I can’t use them. Whenever I try to go to the dashboard it says:
“You’re almost ready to use Mailbutler to boost your email inbox!Click your email client to get your download started. ”

There is no next button and I can’t get rid of the screen despite downloading the app and signing in on gmail.